Touch panel device, touch panel device control method, and non-transitory tangible computer-readable storage medium having the program stored therein

ABSTRACT

A touch panel device having a touch panel includes: a driving unit for sending drive pulse signals to the touch panel; a receiving unit for receiving sense signals based on an operated position on the touch panel; a driving control unit for controlling the driving unit to send the drive pulse signal; a signal strength obtaining unit for obtaining strengths of the sense signals received by the receiving unit; and an operated position obtaining unit for obtaining the operated position based on sense signals, of the sense signals, in which an average of the strengths of the sense signals corresponding to the respective pulses of the drive pulse signal is equal to or greater than a given average and a variance of the strengths of the sense signals corresponding to the respective pulses of the drive pulse signal is less than a given variance.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2018-234312 filed on Dec. 14, 2018, thecontents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a touch panel device having acapacitive touch panel, a touch panel device control method, and anon-transitory tangible computer-readable storage medium having storedtherein a program for causing a computer to execute the touch paneldevice control method.

Description of the Related Art

Conventionally, techniques have been disclosed in which the touchedposition on a touch panel is detected by sensing change in capacitancebased on change in capacitive coupling between the finger and electrodesat the touched position (e.g., Japanese Laid-Open Patent Publication No.2018-106395).

SUMMARY OF THE INVENTION

However, the technique above may incorrectly detect the touched positionsince it also senses change in capacitance caused by noise.

The present invention has been made in order to solve the problem above,and an object of the present invention is to provide a touch paneldevice having high noise immunity, a control method for controlling thetouch panel device, and a non-transitory tangible computer-readablestorage medium having stored therein a program for causing a computer toexecute the touch panel device control method.

According to a first aspect of the present invention, a touch paneldevice including a capacitive touch panel includes: a driving unitconfigured to send a drive pulse signal to the touch panel; a receivingunit configured to receive sense signals based on an operated positionon the touch panel, the sense signals being outputted from the touchpanel; a driving control unit configured to control the driving unit sothat the driving unit sends a given number of pulses of the drive pulsesignals at a given frequency; a signal strength obtaining unitconfigured to obtain strengths of the sense signals received by thereceiving unit; and an operated position obtaining unit configured toobtain the operated position based on sense signals, among the sensesignals, in which an average of the strengths of the sense signalscorresponding to the respective pulses of the drive pulse signal isequal to or greater than a given average and a variance of the strengthsof the sense signals corresponding to the respective pulses of the drivepulse signal is less than a given variance.

According to a second aspect of the present invention, there is provideda method of controlling a touch panel device including a capacitivetouch panel. The touch panel device includes a driving unit configuredto send a drive pulse signal to the touch panel, and a receiving unitconfigured to receive sense signals based on an operated position on thetouch panel, the sense signals being outputted from the touch panel. Thetouch panel device control method includes: a driving control step ofcontrolling the driving unit so that the driving unit sends a givennumber of pulses of the drive pulse signal at a given frequency; asignal strength obtaining step of obtaining strengths of the sensesignals received by the receiving unit; and an operated positionobtaining step of obtaining the operated position based on sensesignals, among the sense signals, in which an average of the strengthsof the sense signals corresponding to the respective pulses of the drivepulse signal is equal to or greater than a given average and a varianceof the strengths of the sense signals corresponding to the respectivepulses of the drive pulse signal is less than a given variance.

A third aspect of the present invention is directed to a non-transitorytangible computer-readable storage medium having stored therein aprogram that causes a computer to execute the touch panel device controlmethod according to the second aspect.

It is possible to improve noise immunity of the touch panel device.

The above and other objects, features, and advantages of the presentinvention will become more apparent from the following description whentaken in conjunction with the accompanying drawings, in which apreferred embodiment of the present invention is shown by way ofillustrative example.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the configuration of a touch paneldevice;

FIG. 2 is a schematic diagram showing a structure of the touch panel;

FIG. 3 is a graph showing drive pulse signals that are inputtedrespectively to Y-axis electrodes from a driving unit;

FIG. 4 is a diagram illustrating nodes on the touch panel;

FIG. 5 is a flowchart showing the flow of an operated position obtainingprocess performed by an operated position obtaining unit;

FIG. 6 is a graph illustrating the drive pulse signals inputted from thedriving unit to the Y-axis electrodes; and

FIGS. 7A, 7B and 7C are tables showing examples of the strengths ofsense signals corresponding to respective pulses.

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment [Configurationof Touch Panel Device]

FIG. 1 is a block diagram showing the configuration of a touch paneldevice 10. The touch panel device 10 is an input device that allows auser to perform an operation by touching a screen of a display unit 12where images etc. are displayed, by using an operating member such as afinger, stylus, etc. The touch panel device 10 of this embodiment isused as an input device for a numerical control device 14 forcontrolling a machine tool not shown.

The touch panel device 10 includes the display unit 12, a displaycontrol unit 16, a touch panel 18, a driving unit 20, a receiving unit22, a driving control unit 24, a signal strength obtaining unit 26, andan operated position obtaining unit 28.

The display unit 12 can be a liquid-crystal display, for example, whichdisplays icons through which a user can enter commands into thenumerical control device 14, information indicating conditions of themachine tool sent from the numerical control device 14, and so on. Thedisplay control unit 16 controls the display unit 12 according torequests from the numerical control device 14.

The touch panel 18 is a transparent film-shaped member put or stuck onthe screen of the display unit 12. The touch panel 18 of this embodimentis a capacitive touch panel. In the description below, an example inwhich the capacitive touch panel is a mutual capacitance touch panelwill be described, but the touch panel 18 may be a self-capacitancetouch panel. The driving unit 20 and the receiving unit 22 are connectedto the touch panel 18.

FIG. 2 is a schematic diagram showing a structure of the touch panel 18.The touch panel 18 includes X-axis electrodes Ex[1] to Ex[m] and Y-axiselectrodes Ey[1] to Ey[n] made of indium tin oxide. The X-axiselectrodes Ex[1] to Ex[m] each extend in the Y-axis direction in FIG. 2,and the electrodes Ex[1] to Ex[m] are arranged in the X-axis directionto form m-lines of electrodes. The Y-axis electrodes Ey[1] to Ey[n] eachextend in the X-axis direction in FIG. 2, and the electrodes Ey[1] toEy[n] are arranged in the Y-axis direction to form n-lines ofelectrodes.

The driving unit 20 is connected to the Y-axis electrodes Ey[1] toEy[n]. The driving unit 20 sends drive pulse signals respectively to theY-axis electrodes Ey[1] to Ey[n]. Hereinafter, the Y-axis electrodesEy[1] to Ey[n] may be collectively referred to as Y-axis electrodes Eywhen it is not necessary to distinguish the lines thereof from eachother.

The receiving unit 22 is connected to the X-axis electrodes Ex[1] toEx[m]. The receiving unit 22 receives current signals respectively fromthe X-axis electrodes Ex[1] to Ex[m]. Hereinafter, the X-axis electrodesEx[1] to Ex[m] may be collectively referred to as X-axis electrodes Exwhen it is not necessary to distinguish the lines thereof from eachother.

Returning to FIG. 1, the driving control unit 24 controls the drivingunit 20 to send the drive pulse signals at a set frequency sequentiallyto the Y-axis electrode Ey[1] to Y-axis electrode Ey[n]. FIG. 3 is agraph illustrating the drive pulse signals inputted from the drivingunit 20 respectively to the Y-axis electrodes Ey. The driving controlunit 24 controls the driving unit 20 so that the driving unit 20 sends120 pulses of the drive pulse signal at the predetermined set frequencysequentially to the Y-axis electrodes Ey. The driving unit 20periodically sends the drive pulse signals respectively to the Y-axiselectrodes Ey[1] to Ey[n], and more specifically sends 120 pulses at atime. The number of pulses of the drive pulse signal is not limited to120 pulses.

From the current signals received at the receiving unit 22 respectivelyfrom the X-axis electrodes Ex, the signal strength obtaining unit 26obtains the strengths of the sense signals at nodes N[1, 1] to N[m, n]on the touch panel 18. The nodes N[1, 1] to N[m, n] may hereinafter becollectively referred to as nodes N when it is not necessary todistinguish them.

When the operating member is not in contact with the touch panel 18,i.e., when the touch panel 18 is not being operated, electric currentflows between the Y-axis electrodes Ey and X-axis electrodes Ex inaccordance with the drive pulse signals. At this time, the amplitude ofthe voltage signal obtained by converting the current signal of anX-axis electrode Ex received by the receiving unit 22 is voltage V0.When the operating member is in contact with the touch panel 18, i.e.,when the touch panel 18 is being operated, current flows also betweenthe Y-axis electrodes Ey and the operating member in accordance with thedrive pulse signals. Accordingly, the current flowing to the X-axiselectrodes Ex when the touch panel 18 is being operated is smaller thanwhen the touch panel 18 is not being operated. At this time, the voltagesignal obtained by converting the current signal of the X-axis electrodeEx received by the receiving unit 22 has an amplitude smaller than thevoltage V0. Using the voltage V0 as a reference voltage, the signalstrength obtaining unit 26 obtains, as the strength of the sense signalat each X-axis electrode Ex, a value corresponding to the difference|V0−V| between the voltage V0 and the voltage V obtained by convertingthe current of each Y-axis electrode Ey received by the receiving unit22.

FIG. 4 is a diagram illustrating the nodes N[1, 1] to N[m, n] on thetouch panel 18. Each node N corresponds to one of the sections definedby dividing the top surface of the touch panel 18 into a matrix ofsections. Each node N is associated with a set of a Y-axis electrode Eyand an X-axis electrode Ex. FIG. 4 shows lines indicating the partitionlines between the nodes N, but the lines indicating the partition linesbetween the nodes N are not visible in an actual touch panel 18.

The signal strength obtaining unit 26 specifies one node N thatcorresponds to a combination of a line of Y-axis electrode Ey to whichthe driving unit 20 has sent the drive pulse signal and a line of X-axiselectrode Ex from which the receiving unit 22 has received the currentsignal. Then, the signal strength obtaining unit 26 obtains the strengthof the sense signal at the X-axis electrode Ex as the strength of thesense signal at the specified node N. For example, if the driving unit20 has sent the drive pulse signal to the Y-axis electrode Ey[3] and thereceiving unit 22 has received the current signal from the X-axiselectrode Ex[4], then the signal strength obtaining unit 26 specifiesthe node N[4, 3]. Then, the signal strength obtaining unit 26 obtainsthe strength of the sense signal of the X-axis electrode Ex[4] as thestrength of the sense signal at the node N[4, 3].

The operated position obtaining unit 28 obtains the operated positiontouched by the operating member in accordance with the strength of thesense signal at each node N obtained by the signal strength obtainingunit 26. The process by which the operated position obtaining unit 28obtains the operated position will be described in detail later.

The display control unit 16, the driving control unit 24, the signalstrength obtaining unit 26, and the operated position obtaining unit 28are realized by a computer executing a program stored in a storagemedium 30. The storage medium 30 is a non-transitory tangiblecomputer-readable storage medium.

[Operated Position Obtaining Processing]

FIG. 5 is a flowchart showing the flow of an operated position obtainingprocess performed by the operated position obtaining unit 28.

At step S1, the operated position obtaining unit 28 selects a first nodeN. The nodes N are selected in the order of node N[1, 1]→node N[2,1]→node N[3, 1]→ . . . →node N[m−1, n]→node N[m, n], for example.

At step S2, the operated position obtaining unit 28 determines whetheror not the average of the strengths of the sense signals correspondingto the respective pulses of the drive pulse signal at the selected nodeN is equal to or greater than a given average (i.e., whether the averageof the sense signal strengths≥the given average). If the average of thestrengths of the sense signals is equal to or greater than the givenaverage, the process moves to step S3; if the average of the strengthsof the sense signals is less than the given average, the process movesto step S5.

At step S3, the operated position obtaining unit 28 determines whether avariance of the strengths of the sense signals corresponding to therespective pulses of the drive pulse signal at the selected node N isless than a given variance (i.e., whether the variance of the sensesignal strengths<the given variance). If the variance of the strengthsof the sense signals is less than the given variance, the process movesto step S4; if the variance of the strengths of the sense signals isequal to or greater than the given variance, the process moves to stepS5.

At step S4, the operated position obtaining unit 28 sets the position ofthe selected node N as the operated position.

At step S5, the operated position obtaining unit 28 determines that thesense signal at the selected node N is noise.

At step S6, the operated position obtaining unit 28 determines whetherthere is a next node N. If there is a next node N, the process moves tostep S7; if there is no next node N, the operated position obtainingprocess terminates.

At step S7, the operated position obtaining unit 28 selects the nextnode N and returns to step S2.

[Functions and Effects]

Capacitive touch panels like the touch panel 18 of the embodiment mightdetect a position not being operated (touched) by the operating member,as an operated position (touched position) because of electric noise. Assuch, methods for determining whether the sense signal is due to noiseor not have been proposed.

FIG. 6 is a graph illustrating the drive pulse signal inputted from thedriving unit 20 to each Y-axis electrode Ey. While, in this embodiment,120 pulses of drive pulse signal are sent to each Y-axis electrode Ey ata time, the explanation below will be given assuming that 4 pulses ofdrive pulse signal are sent to each Y-axis electrode Ey at a time, inorder to simplify the explanation. In addition, as shown in FIG. 6, thepulses of the drive pulse signal are designated by symbols P1 to P4 forthe sake of explanation. The signal strength obtaining unit 26 obtainsthe strengths of the sense signals that correspond to the respectivepulses P1 to P4.

FIGS. 7A, 7B and 7C are tables that show examples of the strengths ofthe sense signals corresponding respectively to the pulses P1 to P4.Usually, the strength of sense signal due to noise is smaller than thestrength of sense signal due to touch (operation). Further, the durationof noise is extremely short and therefore the strength of sense signaldue to noise is detected a smaller number of times during the period ofsending the drive pulse signal at a time. On the other hand, the periodof time during which a touch operation is performed with the operatingmember is longer than the duration of noise and therefore the strengthof sense signal due to touch is detected a larger number of times duringthe period of sending the drive pulse signal at a time. Hence, as shownin FIG. 7A, it is possible to determine that the sense signal is due tonoise if the average of the strengths of the sense signals correspondingto the respective pulses is less than a given average (e.g., givenaverage=500).

However, as shown in FIG. 7B, if extremely intensive noise occurs, theaverage of the strengths of the sense signals due to the noise may beequal to or larger than the given average, so that it is impossible todetermine whether the sense signal is due to noise.

Accordingly, in the touch panel device 10 of this embodiment, theoperated position obtaining unit 28 determines that the sense signal isa sense signal due to noise not only when the average of the strengthsof the sense signals corresponding to the respective pulses is less thana given average but also when the variance of the strengths of the sensesignals corresponding to the respective pulses is equal to or greaterthan a given variance (e.g., given variance=250000). The duration ofnoise is extremely short and the sense signal strengths corresponding tothe respective pulses vary greatly, so that it is possible to accuratelydetermine whether the sense signal is due to noise or not by using thevariance of the strengths of the sense signals (FIG. 7C).

Further, in the touch panel device 10 of this embodiment, the operatedposition obtaining unit 28 obtains the operated position (touchedposition) on the basis of sense signals, of the sense signals, in whichthe average of the strengths of the sense signals corresponding to therespective pulses is equal to or greater than a given average and thevariance of the strengths of the sense signals corresponding to therespective pulses is less than a given variance. This improves noiseimmunity of the touch panel device 10 (FIG. 7C).

[Technical Ideas Obtained from Embodiments]

The touch panel device (10) including a capacitive touch panel (18)includes: a driving unit (20) configured to send a drive pulse signal tothe touch panel; a receiving unit (22) configured to receive sensesignals based on an operated position on the touch panel, the sensesignals being outputted from the touch panel; a driving control unit(24) configured to control the driving unit such that the driving unitsends a given number of pulses of the drive pulse signal at a givenfrequency; a signal strength obtaining unit (26) configured to obtainstrengths of the sense signals received by the receiving unit; and anoperated position obtaining unit (28) configured to obtain the operatedposition based on sense signals, among the sense signals, in which theaverage of the strengths of the sense signals corresponding to therespective pulses of the drive pulse signal is equal to or greater thana given average and a variance of the strengths of the sense signalscorresponding to the respective pulses of the drive pulse signal is lessthan a given variance. It is thus possible to improve noise immunity ofthe touch panel device.

In a method of controlling a touch panel device (10) including acapacitive touch panel (18), the touch panel device includes a drivingunit (20) configured to send a drive pulse signal to the touch panel,and a receiving unit (22) configured to receive sense signals based onan operated position on the touch panel, the sense signals beingoutputted from the touch panel. The touch panel device control methodincludes: a driving control step of controlling the driving unit suchthat the driving unit sends a given number of pulses of the drive pulsesignals at a given frequency; a signal strength obtaining step ofobtaining strengths of the sense signals received by the receiving unit;and an operated position obtaining step of obtaining the operatedposition based on sense signals, among the sense signals, in which theaverage of the strengths of the sense signals corresponding to therespective pulses of the drive pulse signal is equal to or greater thana given average and a variance of the strengths of the sense signalscorresponding to the respective pulses of the drive pulse signal is lessthan a given variance. It is thus possible to improve noise immunity ofthe touch panel device.

Further, there is provided a program that causes a computer to executethe touch panel device (10) control method described above. It is thuspossible to improve noise immunity of the touch panel device.

Yet further, there is provided a non-transitory tangiblecomputer-readable storage medium (30) having stored therein a programthat causes a computer to execute the touch panel device (10) controlmethod described above. It is thus possible to improve noise immunity ofthe touch panel device.

The present invention is not particularly limited to the embodimentdescribed above, and various modifications are possible withoutdeparting from the essence and gist of the present invention.

What is claimed is:
 1. A touch panel device including a capacitive touchpanel, comprising: a driving unit configured to send a drive pulsesignal to the touch panel; a receiving unit configured to receive sensesignals based on an operated position on the touch panel, the sensesignals being outputted from the touch panel; a driving control unitconfigured to control the driving unit so that the driving unit sends agiven number of pulses of the drive pulse signal at a given frequency; asignal strength obtaining unit configured to obtain strengths of thesense signals received by the receiving unit; and an operated positionobtaining unit configured to obtain the operated position based on sensesignals, among the sense signals, in which an average of the strengthsof the sense signals corresponding to the respective pulses of the drivepulse signal is equal to or greater than a given average and a varianceof the strengths of the sense signals corresponding to the respectivepulses of the drive pulse signal is less than a given variance.
 2. Amethod of controlling a touch panel device including a capacitive touchpanel, wherein the touch panel device comprises: a driving unitconfigured to send a drive pulse signal to the touch panel; and areceiving unit configured to receive sense signals based on an operatedposition on the touch panel, the sense signals being outputted from thetouch panel, the touch panel device control method comprising: a drivingcontrol step of controlling the driving unit so that the driving unitsends a given number of pulses of the drive pulse signal at a givenfrequency; a signal strength obtaining step of obtaining strengths ofthe sense signals received by the receiving unit; and an operatedposition obtaining step of obtaining the operated position based onsense signals, among the sense signals, in which an average of thestrengths of the sense signals corresponding to the respective pulses ofthe drive pulse signal is equal to or greater than a given average and avariance of the strengths of the sense signals corresponding to therespective pulses of the drive pulse signal is less than a givenvariance.
 3. A non-transitory tangible computer-readable storage mediumhaving stored therein a program that causes a computer to execute thetouch panel device control method according to claim 2.